src/backend/libpq/README.SSL

   1 $PostgreSQL$
   2
   3 SSL
   4 ===
   5
   6 >From the servers perspective:
   7
   8
   9   Receives StartupPacket
  10            |
  11            |
  12  (Is SSL_NEGOTIATE_CODE?) -----------  Normal startup
  13            |                  No
  14            |
  15            | Yes
  16            |
  17            |
  18  (Server compiled with USE_SSL?) ------- Send 'N'
  19            |                       No        |
  20            |                                 |
  21            | Yes                         Normal startup
  22            |
  23            |
  24         Send 'S'
  25            |
  26            |
  27       Establish SSL
  28            |
  29            |
  30       Normal startup
  31
  32
  33
  34
  35
  36 >From the clients perspective (v6.6 client _with_ SSL):
  37
  38
  39       Connect
  40          |
  41          |
  42   Send packet with SSL_NEGOTIATE_CODE
  43          |
  44          |
  45   Receive single char  ------- 'S' -------- Establish SSL
  46          |                                       |
  47          | '<else>'                              |
  48          |                                  Normal startup
  49          |
  50          |
  51    Is it 'E' for error  ------------------- Retry connection
  52          |                  Yes             without SSL
  53          | No
  54          |
  55    Is it 'N' for normal ------------------- Normal startup
  56          |                  Yes
  57          |
  58    Fail with unknown
  59
  60 ---------------------------------------------------------------------------